[OT] Sudoku again: How to find a sudoku?

(Ralf Müller) #1

Hi out there,

What i like to know, is how could you know, that a sudoku-like number table is
a real sudoku with only ONE SINGLE solution?

The Solvers from the quiz (which I did not read) will surely find a solution.
But where did the sudokus themselves came from?

What about a sudoku-generator? Which leads to: How to proof a certain number
table has one and only one solution?

Maybe the solvers do that already? And if so, which one does?

Sorry for the memo-style onf the message. It just came to my mind and had to be
written down.

regards
ralf

···

--

"not using Ruby is punishment enough"
  -- James Britt, 8.5.2005, ruby-talk@ruby-lang.org

(Alpha Chen) #2

For those of you interested in pursuing some more Sudoku programming, there's a programmer's forum for it here: http://www.setbb.com/phpbb/?mforum=sudoku

I think most programs solve the puzzle by use of only logic, which would mean that there would only be one solution. Or if there must be guessing (using the Nishio method, I suppose), then you'd make sure that there's only one branch that correctly solves the puzzle. Some also start from a finished puzzle and move backwards logically to create a starting set.

Alpha Chen

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On Aug 26, 2005, at 2:08 AM, Ralf Müller wrote:

What i like to know, is how could you know, that a sudoku-like number table is
a real sudoku with only ONE SINGLE solution?

The Solvers from the quiz (which I did not read) will surely find a solution.
But where did the sudokus themselves came from?

What about a sudoku-generator? Which leads to: How to proof a certain number
table has one and only one solution?

(James Edward Gray II) #3

Hi out there,

What i like to know, is how could you know, that a sudoku-like number table is
a real sudoku with only ONE SINGLE solution?

The solution I discussed in the summary does distinguish between multiple solution puzzles and single solution puzzles.

The Solvers from the quiz (which I did not read) will surely find a solution.
But where did the sudokus themselves came from?

What about a sudoku-generator? Which leads to: How to proof a certain number
table has one and only one solution?

This probably doesn't exactly answer your question, but this site appears to hold monthly contests:

http://www.sudoku.com/

That amounts to a new puzzle each month.

James Edward Gray II

···

On Aug 26, 2005, at 1:08 AM, Ralf Müller wrote:

(Ralf Müller) #4

Many thanks for the links!!!

Exactly what I was looking for.

best regards
ralf

···

--

"not using Ruby is punishment enough"
  -- James Britt, 8.5.2005, ruby-talk@ruby-lang.org